Revolving door operating and speed control mechanism

ABSTRACT

The power drive and speed control means for a revolving door along with related electrical control circuitry and mechanical components are all contained compactly in the center shaft or column of the door structure. Costly and time-consuming servicing of parts mounted in the ceiling or floor is eliminated.

United States Patent [191 Sheckells Oct. 23, 1973 [54] REVOLVING DOOROPERATING AND l,342,253 6/1920 Collins 49/46 SPEED CONTROL MECHANISM3,526,820 9/1970 Sheckells 4. 49/43 X Amuel E. Sheckells, Evansville,Ind.

[75] Inventor:

[73] Assignee: International Steel Company, Primary Karl I EvansvilleInd. Attorney-Rupert J. Brady et al.

221 Filed: Dec. 21, 1971 [21] App]. No.: 210,385 6 7] ABSTRACT [52][1.5. CI. 49/43, 188/185 The power drive and speed control means for are- [51] Int. Cl. E051! 15/02 volving door along with related electricalcontrol cir- [58] Field of Search 49/42-47 uitry and mechanicalcomponents are all contained compactly in the center shaft or column ofthe door References Cited structure. Costly and time-consuming servicingof UNITED STATES PATENTS parts mounted in the ceiling or floor iseliminated. 2,050,584 8/1936 Peremi 'et al 49/43 0 r W 19 Claims, 9Drawing Figures 3 I6 4 I 83 l5 "/vi 7 :L:

I09 r a l v z 70 20 83 I I y Patented Oct. 23, 1973 4 Sheets-Sheet 2Patented Oct. 23, 1973 3,766,686

4 Sheets-Sheet 5 F I05 H06 'I I I III I Patented Oct. 23, 1973 4Sheets-Sheet 4 REVOLVING DOOR OPERATING AND SPEED CONTROL MECHANISMBACKGROUND OF THEINVENTION The revolving door art has been considerablyimproved and refined in recent years in the interest of economy ofmanufacturing and installation, reliability of operation and safety. Forexample, in prior art US. Pats. to Sheckells, No. 3,307,660 and No.3,349,876, dated respectively Mar. 7, 1967 and Oct. 31, 1967, lowprofile speed control mechanisms for revolving doors are disclosed whichinclude highly compact centrifugal brake mechanisms and coactingcontinuous lubrication means. In the later of the above Sheckellspatents, a motor drive and clutch arrangement is disclosed incombination with centrifugal brake means and a lubricating pump. In aneven more recent Sheckells US. Pat., No. 3,497,997, dated Mar. 3, 1970,a quarter-line electrical stop control system for revolving doors isdisclosed assuring immediate and easy starting of the power operateddoor in response to finger tip pressure, followed by a smooth controlledspeed cycle of operation and a safe slowing to an automatic stop at thequarterline position. These patented prior art features have advancedthe'revolving door art to a state of relatively high sophistication andhave eliminated many of the chief deficiencies and inconveniences of theolder prior art which, to someextent, have hindered public acceptanceand commercial acceptance of revolving doors,

despite numerous recognized advantages inherent therein.

In spite of the relatively advanced state of the art, at least onepersistent problem has remained unsolved with the result thatinstallation and maintenance costs for revolving doors remain relativelyhigh. More particularly, this problem is concerned with the placement ofoperating and speed control mechanisms and associated components forrevolving doors either in the ceiling above the door or in theunderlying floor structures. In spite of great improvement in thecompactness and relatively simplicity of these mechanisms, the necessityfor mounting them above or below the door proper and for servicing themechanisms in these locations continues to be rather awkward andexpensive.

It is therefore the object of the present invention to completelyeliminate'this continuing difficulty or problem by arranging all of theoperating and control components within the center shaft of therevolving door in such a way that initial installation and subsequentservicing of the door is rendered much more convenient and economical.In effect, the revolving door becomes substantially a sefl-containedassembly or unit which can be bodily removed from the doorway withlittle difficulty in the event that major maintenance operations arenecessary. The only components remaining in the ceiling and floor are asimple overhead vibration absorber and a bottom support bearing for thedoor structure. The center shaft which contains the power drive andspeed control elements as well as the quarterline stopping means isconstructed in such a manner as to be relatively simple to disassemblewhen necessary for maintenance. The particular power drive and speedcontrol elements of the mechanism have the ability by virtue of theirvery compact design to be contained totally in the center shaft of thedoor without rendering the center shaft excessively large and thuspreserving the architectural merits of the door construction.

Other features and advantages of the invention will become apparentduring the course of the following detailed description.

BRIEF DESCRIPTION OF DRAWING FIGURES FIG. 1 is a side elevation of arevolving door embodying the present invention FIG. 2 is an enlargedfragmentary central vertical section taken through the center shaft andassociated elements of the revolving door, partly in elevation.

FIG. 3 is an enlarged fragmentary central vertical section through thespeed control mechanism and associated elements in the center shaft.

FIG. 4 is an enlarged horiz'ontal section taken on line 4-4 of FIG. 3.

FIG. 5 is a similar section taken on line 5-5 of FIG.

DETAILED DESCRIPTION Referring to the drawings in detail wherein likenumerals designate like parts, the numeral 10 designates a revolvingdoor in its entirety, of the type consisting of four circumferentiallyequidistantly spaced Wings 11 radiating from a vertical center shaft 12.The revolving door according to the invention is substantially aselfcontained assembly or unit and is installed between a ceilingstructure 13 and floor 14 in a very expeditious and simplified manner.More particularly, the top relatively stationary cylindrical sleeve 15forming the upper end of the center shaft 12 has a radial flange 16connected by a suitable number of bolts 17 to a blocklike element 18 ofvibration-absorbing material. The

element 18 lies snugly between a pair of horizontal ceiling joists 19and rests on the bottom plate of the ceiling structure, as shown in FIG.2. Through the yielding element 18, the upper end of the center shaft 12is firmly held and is insulated against shocks and vibrations.

The .entire revolving door 10 including the center shaft 12 is supportedon'the 'floor 14 through a short upstanding stub shaft 20 resting on abase 21 which is recessed into the floor 14. A .suitable low frictionthrust-type bearing 22 on the stub shaft 20 supports the revolving doorby being recessed into a cap or plug 23, secured rigidly in the bore ofa lower end sleeve 24 constituting the bottom terminal of the centershaft 12 and being a rotational component of the center shaft. Thus, theentire door structure has a simplified two point support through the topand bottom terminals of the center shaft 12, whereby installation andremoval of the door is greatly simplified.

Within the lower end portion of the top non-rotatable sleeve 15 is adoor drive motor 25 having a central depending drive shaft 26 adapted torevolve at approximately 750 RPM. The space above the motor 25 in thebore of the sleeve 15 is utilized to house the electronic controls forthe quaterline stop system substantially as disclosed in the priorSheckells US. Pat. No.

3,497,997. These electronic controls in the sleeve are indicateddiagrammatically at 27 in FIG. 2. The casing of drive motor is fixedlysecured by bolt means 28 to a ring 29 in the lower end of sleeve 15 andfixed to the sleeve so as to become a part of the nonrotating section ofthe center shaft 12. An upwardly open cup-like coupling 30 hasscrew-threaded engagement within the ring 29, FIG. 3, and has a bottomwall 31 recessed to receive a ball bearing 32 or the like.

Immediately below the coupling 30 in the center shaft 12 is a harmonicdrive 33 or speed reducer substantially of the type disclosed in U.S.Pat. No. 2,906,143 to Musser dated Sept. 29, 1959. This harmonic driveis manufactured and sold by USM Corporation, Gear Systems Division, asModel IM. The harmonic drive 33 embodies a central vertical input shaft34 connected by a rigid coupling 35 with the drive shaft 26 of motor 25.The coupling 35 contains a one-way active and one-way free wheelingclutch 36, such as a Torrington roller clutch, and the input shaft 34 ofthe harmonic drive is driven through this clutch 36, as shown in FIG. 3,the clutch rendering the shaft 34 freewheeling or free-turning in thesame direction in which it is driven whenever the speed of the shaft 34exceeds the driving speed of the shaft 26. The harmonic drive 33 furthercomprises, as disclosed in the Musser patent, an elliptical bearing 37driven by a loose fit connector 38 on the input shaft 34. The outer race39 of elliptical bearing 37 is received within the bore of a thin-wallednormally cylindrical cup 40 having a multiplicity of spline teeth 41 onthe exterior thereof around the top open end of the cup. The side wallof cup 40 will flex or deflect radially in response to rotation of theelliptical bearing 37 and the points of deflection in the cup wall willadvance circumferentially around the cup during the unique action ofthis drive, as explained in the Musser patent.

Surrounding the upper end portion of the cup 40 adjacent to its teeth 41is a rigid internally toothed ring gear 42 whose teeth 43, FIG. 4, willbe intermittently engaged at two opposing positions with the teeth 41 ofthe deflectable cup 40 as the elliptical bearing 37 rotates.Approximately 20 teeth on the cup 40 will be engaged with the ring gearteeth at any one time. As the wall of the cup 40 is deflected in and outduring turning of the elliptical bearing, the cup teeth 41 are pushedinto engagement with the ring gear teeth, and due to a difference in thenumber of teeth on the cup and ring gear, the cup will gradually revolverelative to the ring gear. In practice, there may be one hundred of theteeth 41 on the cup and one hundred and two teeth on the surroundingring gear 42. With this arrangement, the cup 40 will glide over twoteeth on the ring gear during each revolution of the bearing 37, thusimparting the desired rotational speed to the rotary section of the doorcenter shaft 12. With the motor shaft 26 turning at 1750 RPM, there willbe a 200:1 speed reduction through the drive 33 with the describedembodiment of the drive, and the revolving door shaft will be driven atapproximately 8.8 RPM which is a safe walking speed for users of thedoor. A constantly advancing sinusoidal deflection wave is set up in thecup side wall due to the movement of the balls in bearing 37 around theelliptical race of the bearing.

The ring gear 42 is held against rotation by screws 44 and through thesescrews is joined rigidly to the coupling 30 and thus becomes a part ofthe non-rotating section of the door center shaft 12 along with the topsleeve 15. The same screws 44 also join the ring gear 42 to another ringsection 45 directly therebelow and a reduced diameter extension 46 onthe bottom of this ring section serves as a seat for another lowfriction bearing 47 which is interposed between the nonrotating androtating sections of the center shaft 12.

In this latter connection, the bottom wall 48 of the cup 40 is securedby screws 49 to the upper section 50 of a shock-absorbing Bostoncoupling. This coupling which is of a well known type embodies acoacting lower section 51. As best shown in FIG. 6, the two sections 50and 51 of the Boston coupling have upwardly and downwardly directedinterdigitating fingers 52 and 53 intervened by circumferentially spacedresilient fingers or strips 54, radiating from a center resilient body55. The harmonic drive 33 tends to create a cyclic vibration in thecenter'shaft 12 and this Boston coupling is very effective in absorbingthe vibration and eliminating it. The Boston coupling composed of thetwo sections 50 and 51 being joined to the cup 40 of the drive 33becomes a part of the rotating section of the center shaft 12.Surrounding the Boston coupling and the harmonic drive 33 and stationarycomponents 31, 42 and 45 is an external sleeve 56 also forming a part ofthe rotating section of the door center shaft. This sleeve is fixed tocoupling part 50 by screws 57. The top end of the rotating sleeve 56overlaps an annular seal 58 mounted on an annular shoulder 59 of thenonrotating coupling 30. This establishes an oil barrier or seal betweenthe non-rotating and rotating sections of the door center shaft 12.

An additional ring 60 immediately above the seal 58 is secured suitablyto the sleeve 56 and rotates therewith. On its interior, the rotatingring 60 carries an arcuate magnetic strip element 61, FIG. 8, whichcorresponds to the magnetic strip 23 in the Sheckells U.S. Pat. No.3,497,997 and functions in precisely the same manner to provide theautomatic quarterline stop feature disclosed in said patent. Theteachings of this Sheckells patent concerning the quarterline stopcontrol system are incorporated by reference totally into the disclosureof this application, and therefore it is unnecessary to completelydescribe the quarterline stop control system herein. The nonrotatingring 29 contains embedded therein a plurality of magnetic reed switches62 whose spacing and relation to the magnetic strip 61 is essentiallyidentical to the arrangement of the reed switches in U.S. Pat. No.3,497,997, and the switches 62 operate in the same manner in connectionwith the control circuitry as disclosed in the Sheckells patent.Whenever there is relative rotation between the non-rotary and rotarysections of the center shaft 12, there will be corresponding relativerotation between the magnetic strip 61 and the reed switches 62 In orderto regulate and limit the rotational speed of the revolving door 10, acentrifugal brake mechanism is utilized in conjunction with the harmonicdrive 33. This brake mechanism is shown in FIGS. 3 and 5 and comprises apair of back-to-back massive semi-circular shoes 63 having frictionlinings 64, the shoes being contained inside of a cup-like drum 65 whosebottom wall is fixedly secured by the screws 49 to the section 50 of theBoston coupling and to the cup 40. Therefore, the drum 65 turns with thecup 40 and the other related parts which make up the rotational portionof the center shaft 12.

However, as will be fully explained, there can be relative rotationalmovement between the brake shoes 63 and the drum 65 and to facilitatethis relative movement, the two shoes 63 are coupled to the input shaft34 of drive 33 by diametrical pins 66 anchored within openings 67 of theshaft 34 and extending slidably into radial guide openings 68 of thebrake shoes. The brake shoes are adapted to expand outwardly along theguide pins 66 under the influence of centrifugal force until the linings64 engage the drum 65. Expansion of the shoes 63 is resisted by springs65'FIG. 3, mounted on headed pins which are anchored to the adjacentportion of shaft 34. The lower end of the shaft 34 is journaled within alow friction bearing 69 held in a recess of the coupling section 50 sothat relative rotation can occur at proper times between the shaft 34and the drum 65 and associated parts. The bearing 32 in a similar mannerforms. a journal for the upper portion of shaft 34 which must alsorotate relative to the stationary elements of the center shaft 12, allpreviously identified.

The revolving door 12 additionally comprises hanger or suspension meansfor the door wings 11 on the center shaft 12. This hanger means is intwo sections or units 70 on the center shaft 12 above and below thevertical center of the door, FIG. 1. The details of one hanger unit areshown primarily in FIGS. 3 and 7, it being understood that the two units70 are identical and therefore a description of one unit will serve todescribe both. It should be pointed out that both hanger units 70 arecarried by the revolving portion of the door center shaft 12.

vThe upper unit 70 of the hanger means, referring to FIGS. 3 and 7,comprises a coupling 71 immediately below the lower section 51 of theBoston coupling and having a firm screw-threaded connection therewith asshown at 72. The coupling 71 forms another segment of the rotatingsection of the center shaft 12 below the Boston coupling. Under thecoupling 71 in stacked concentric relation are four sturdy hanger rings73 for the four wings 11 of the door. The lower hanger unit 70 similarlyembodies four hanger rings 73. Referring to FIG. 3, the several rings-73are separated by low friction bearings 74 and a similar bearing 75 isplaced beneath the lowermost hanger ring 73 and an underlying disc orplug 76. A similar disc 76 lies below the lowermost ring 73 of the lowerhanger unit 70, FIG. 2. Still another disc 77 of a similar nature isdisposed above the uppermost ring 73'.

The discs 76 and 77 are disposed in the end portions of a verticalcylindrical tube section 78 forming an intermediate part of therevolving portion of center shaft 12, FIG. 1. The disc 76' and the plug23, FIG. 2, are similarly held in the lower sleeve 24 which constitutesthe lowermost section of the revolving part of the door center shaft.The elements 71, 73 and 76, FIG. 3, and the elements 77, 73' and 76FIG.2, all receive through Each door leaf 11 has a marginal frame or molding83 and each interior vertical section of the door wing moldings adjacentthe center shaft 12 carries a rigid solid framing bar 84, these barsbeing held in bearing parts 85 on the moldings 83, FIG. 7. The framingbars 84 are preferably constructed in sections which are joined adjacentto the units 70 by dowel type socket connections 86, where theinterfitting pin and socket elements are polygonal in cross section. Thetop and bottom extremities of the framing bars 84 are splined at 87 tohorizontal framing bars 88 in the tops and bottoms of the door wingmoldings. In a similar manner, the horizontal bars 88 are connected tovertical framing bars, not shown, on the outer sides of the door wings.Thus, each wing 11 is framed by a system of rigid barsso that the wingcannot sag or be deflected which would cause breakage of glass.Additionally, the vertical bars 84, as will now be described, form thewing supporting elements which connect with the hanger or suspensionrings 73 and 73.

Continuing to refer to FIGS. 3 and 7, the hanger rings 73 and 73' eachhave a single radial knuckle 89 projecting therefrom at onecircumferential point. The knuckles 89 of rings 73 and the correspondingknuckles 89' of rings 73 are spaced 90 circumferentially from theknuckles of rings immediately above and below. This arrangementestablishes the proper circumferential spacing of the door wings 11around the center shaft 12. As illustrated in FIG. 3, the severalknuckles 89 receive reduced diameter sections 84' of the bars 84 andthis is also illustrated in FIG. 7. Associated with each knuckle 89 is ayielding pin detent 90 on the parconnection between the wings 11 and therotating portion of the center shaft 12.

aligned central axial openings at center hanger shaft 79 Thus, thecenter hanger shaft 79 is fixed and non-' rotatable relative to theseveral rings 73 and 73'although it forms a part of the rotating portionof the door center shaft 12.

A second or back-up or safety release for the revolving door is providedby the inclusion of an additional spring-loaded detent 92 on each ring73 and 73inwardly of the detents 90. Detent pins 92 engage releasably inrecesses 93 formed in the hanger center shaft 79 at intervals. Thisdouble release arrangement on the door wings allows the four wings toyield under torque loading and collapse into parallelism like the leavesof a book. If there was only a single collapse point for each wing atthe center axis of the door, the wings could collapse under pressure butcould not be pressed around into the desired compact formation becausethe rigid wings could not wrap around the center shaft. Consequently,the double jointed arrangement is required. This wing foldingarrangement is necessary on all revolving doors so that people underpanic conditions can pass through the doorway in two streams of trafficwithout having the wings impede their travel.

Returning to the operation of the speed control means for the revolvingdoor 10, it should be mentioned that the door may be motor-driven asshown and described, or may be manually operated without a motor andtherefore without the electrical quarterline stop feature of U.S. Pat.No. 3,497,997. In the illustrated arrangement where the motor 25 and thequarterline stop control system of US. Pat. No. 3,497,997 are employed,the motor shaft 26 will be driven at approximately 1750 RPM, and throughthe one-way active clutch 36, the input shaft 34 of harmonic drive 33will be driven at a similar speed. The centrifugal brake means will notbe activated at this time because the springs 65' resist application ofthe brake until a speed somewhat in excess of the motor shaft speed isreached, as when someone attempts to operate the revolving door at arunning speed rather than a safe walking speed.

With the shaft 34 turning at normal motor shaft speed, the eccentricbearing 37 of the harmonic drive is turned by the loose fit connector 38and the previously-described advancing deflection wave is set up in thecup 40 and due to the difference in the number of teeth 41 on the cupand. the number of teeth 43 on the non-rotating ring gear 42, thepreviously described 200:1 reduction in speed between the motor shaft 26and the cup 40 will be achieved. This means that the cup 40 and allparts of the center shaft 12 secured thereto will now revolve atapproximately 8.8 RPM which is a safe walking speed. Because of theutilization of the reed switches 62 and magnetic strip 61 and therelative rotational movement of these parts, the quarterline automaticstop and the finger tip pressure startup of the revolving door will takeplace exactly as disclosed in the Sheckells US. Pat. No. 3,497,997 andtherefore this important feature has also been built bodily into thecenter shaft 12 along with the speed controller and other associatedcomponents.

Whenever someone pushes against one of the leaves 11 while walking orrunning through the revolving door at more than a safe speed, suchpushing force is transmitted from the door wing through the hanger andsafety detent structure shown in FIGS. 3 and 7 to the revolving sectionof the center shaft 12. This revolving section includes the cup 40 ofthe harmonic drive. This cup will now be forced to turn at a greaterrate of speed than normally produced by the driving motor 25 but will beturning in the same direction. Therefore, the harmonic drive 33 willbegin to operate in an opposite manner as a speed increaser, rather thana speed reducer, back through the interengaging teeth 41 and 43 andthrough the eccentric bearing 37 and shaft 34. The one-way active clutch36 will permit the shaft 34 to revolve in the same direction at a speedgreater than the 1,750 RPM produced by the motor shaft 26. This greaterspeed will reach a degree approximately when the user of the revolvingdoor 10 causes it to turn more than 12' RPM sufficient to overcome therestraining force of the springs 65' and the resulting centrifugal forceat the speed above 1,750 RPM will cause application of the centrifugalbrake. That is to say, the shoes 63 will shift radially outwardly andthe linings 64 will contact the interior of drum 65 and the revolvingcomponent of the center shaft 12 carrying the wings I 1 will be gentlyslowed down to a safe speed automatically, such safe speed not exceedingthe normal approximately 12 RPM established and maintained by thedriving motor 25. This automatic braking action on the revolving doorwill occur whenever a user pushes the door at more than a prescribedsafe speed. When the speed of the door has returned to normal, the motor25 again takes over and continues to drive the door at a normal speedbelow that at which the brake will be activated by centrifugal force,namely, not exceeding 1,750 RPM.

In cases where the revolving door is not power-driven and no motor isinvolved, the door is pushed manually in the customary manner fornon-powered doors. However, in this situation, whenever the user speedsup the door beyond the predetermined safe speed, the harmonic drive 33will regulate the speed by causing application of the centrifugal brakemeans in the same manner described immediately above where the userrevolves the door in excess of the speed established by a motor. That isto say, the excessive speed will be transmitted to the shaft 34 throughthe drive 33 as a speed in excess of that at which the brake will remaininactive. As a consequence, the invention speed controller operatesessentially the same with or without a power drive.

In FIG. 9, a modification is shown wherein the arrangement of theharmonic drive 94 is reversed in com-,

parison to the drive 33 in the previous embodiment. That is to say, inFIG. 9, the ring gear 95 having the internal spline teeth 96 is securedas at 97 to a revolving component 98 of the door center shaft 99 insteadof to a fixed component as in the prior embodiment. The cup-likedeflectable gear 100 with the external teeth 101 is inverted relative tothe cup 40 in FIG. 3 and is attached at 102 along with an inverted brakedrum 103 to a fixed coupling part 104 of the door center shaft 99.

FIG. 9 additionally shows a drive motor 105 similar to the motor 25inside of fixed sleeve 106 and the shaft of this motor is coupled to acenter drive shaft 107 through a one-way engaging clutch 108corresponding to the clutch 36 in FIG. 3. The drive shaft 107 isjournaled for independent rotation in bearings 109 and 1 l0 and thelower end of the shaft 107 is coupled with and drives an ellipticalbearing 111 through a loose fit connector 112 similar to the connector38. The elliptical bearing engages inside of the lower end of the cupgear 100 near the teeth 101 and 96.

As in the prior embodiment, the centrifugal force actuated brake shoes113 are pinned to the shaft 107 by guide pins 1 14, which pins slidablyengage within radial openings of the shoes. Radial expansion of theshoes is resisted by springs 115 whose tension may be adjusted.

In FIG. 9, the previously-described quarterline stop control means isindicated, the reed switches 116 being carried by the fixed element 104adjacent to the mag netic strip 117 carried by the rotatable part 98 ofthe center shaft.

The mode of operation of the dirve and speed controller is essentiallyidentical to the mode of operation in the prior embodiment except forthe described reversal of the gears 95 and 100 and associated elementsand it is believed that the description need not be repeated for a fullunderstanding of the modification by shaft being at least in partrotatable on the longitudinal axis thereof, radiating circumferentiallyspaced door wings attached to the center shaft and revolving with therotatable part of the center shaft in the doorway, and speed controlmeans for the revolving door mounted bodily inside of said center shaft.

2. The structure of claim 1, and said speed control means for therevolving door comprising a rotational speed changing drive within thecenter shaft coupled to the rotatable part of the center shaft, and acentrifugal force actuated brake means coupled to said drive and adaptedto engage an element of said rotatable part of the center shaft whensaid drive causes rotation of the brake means at a speed in excess of aprescribed rotational speed.

3. The structure of claim 2, and a drive motor for the revolving doorinside of said center shaft and having a driving connection with saidspeed changing drive.

4. The structure of claim 3, and said center shaft comprising a fixedsection and a rotatable section, said rotational speed changing drivehaving a connection with each section of the center shaft, and coactingelectrical means on the fixed and rotatable sections of the center shaftassociated with said drive motor and operable to stop the revolving doorautomatically at a quarterline position and also initiating the startingof the revolving door in response to manual pressure thereon.

5. The structure of claim 2, and a resilient coupling means in therotatable part of said center shaft to absorb torsional vibrationscreated by said rotational speed change drive.

6. The structure of claim 2, and hanger means for said door wings on therotatable part of the center wings to collapse in response to excessivemanual pressure thereagainst.

8. The structure of claim 4, and a lubricant seal interposed betweensaid fixed and rotatable center shaft sections.

9. The structure of claim 1, and support means for the ends of thecenter shaft adjacent said ceiling and floor structures and beingsubstantially flush with the exterior faces of the ceiling and floorstructures.

10. The structure of claim 9, and said support means for the lower endof the center shaft adjacent the floor structure including a lowfriction bearing having a connection with the rotatable part ofthe-center shaft, and means to anchor the bearing to the floorstructure.

11. The structure of claim 9, and said support means for the upper endof the center shaft adjacent the ceiling structure comprising aresilient body attached to the ceiling structure and secured to anon-rotatable part of the center shaft.

12. The structure of claim 4, and electrical control circuitry for saiddrive motor and coacting electrical means disposed inside of said centershaft.

13. The structure of claim 3, and said center shaft comprising fixed androtatable sections, said rotational speed changing drive including agear element anchored to one of said sections of the center shaft, acoacting deflectable gear element attached to the other of said sectionsand positioned to engage the first-named gear element, an eccentricoperator for said deflectable gear element connected with and driven bysaid motor and operable to create a circumferentially travelingdeflection wave in the deflectable gear element to thereby inducerelative rotation between said deflectable and first-named gearelements, and a centrifugal force actuated brake means connected withand driven by said eccentric operator and adapted when activated toarrest relative rotation between said fixed and rotatable sections ofthe center shaft.

14. The structure of claim 13, and said deflectable gear elementcomprising a thin-walled cup-like element arranged within thefirst-named gear element, the firstnamed gear element being a ring gear,a brake drum arranged inside of said cup-like element and secured to oneof said sections of the center shaft, and said brake means comprisingradially expansible brake shoes arranged inside of said drum.

15. The structure of claim 13, wherein the firstnamed gear element isanchored to said fixed section of the center shaft and said deflectablegear element is attached to the rotatable section of the center shaft.

16. The structure of claim 13, and said first'named gear element isanchored to the rotatable section of the center shaft, and saiddeflectable gear element is attached to the fixed section of the centershaft.

17. The structure of claim 13, and a driving shaft for said brake meanshaving a connection with said eccentric operator and coupled with anddriven by said drive motor.

18. The structure of claim 17, and a one-way active clutch couplingbetween said driving shaft and motor.

19. The structure of claim 18, and said eccentric operator comprising anelliptical bearing element coupled to said driving shaft and engaginginside of said deflectable gear element.

1. A revolving door comprising a center shaft adapted to be positionedin a doorway between the ceiling and floor structures of said doorway,said center shaft being at least in part rotatable on the longitudinalaxis thereof, radiating circumferentially spaced door wings attached tothe center shaft and revolving with the rotatable part of the centershaft in the doorway, and speed control means for the revolving doormounted bodily inside of said center shaft.
 2. The structure of claim 1,and said speed control means for the revolving door comprising arotational speed changing drive within the center shaft coupled to therotatable part of the center shaft, and a centrifugal force actuatedbrake means coupled to said drive and adapted to engage an element ofsaid rotatable part of the center shaft when said drive causes rotationof the brake means at a speed in excess of a prescribed rotationalspeed.
 3. The structure of claim 2, and a drive motor for the revolvingdoor inside of said center shaft and having a driving connection withsaid speed changing drive.
 4. The structure of claim 3, and said centershaft comprising a fixed section and a rotatable section, saidrotational speed changing drive having a connection with each section ofthe center shaft, and coacting electrical means on the fixed androtatable sections of the center shaft associated with said drive motorand operable to stop the revolving door automatically at a quarterlineposition and also initiating the starting of the revolving door inresponse to manual pressure thereon.
 5. The structure of claim 2, and aresilient coupling means in the rotatable part of said center shaft toabsorb torsional vibrations created by said rotational speed changedrive.
 6. The structure of claim 2, and hanger means for said door wingson the rotatable part of the center shaft.
 7. The structure of claim 6,and said hanger means including pivotal bearing supports for the doorwings, and yielding detent means carried by the hanger means andengageable with said wings and permitting the wings to collapse inresponse to excessive manual pressure thereagainst.
 8. The structure ofclaim 4, and a lubricant seal interposed between said fixed androtatable center shaft sections.
 9. The structure of claim 1, andsupport means for the ends of the center shaft adjacent said ceiling andfloor structures and being substantially flush with the exterior facesof the ceiling and floor structures.
 10. The structure of claim 9, andsaid support means for the lower end of the center shaft adjacent thefloor structure including a low friction bearing having a connectionwith the rotatable part of the center shaft, and means to anchor thebearing to the floor structure.
 11. The structure of claim 9, and saidsupport means for the upper end of the center shaft adjacent the ceilingstructure comprising a resilient body attached to the ceiling structureand secured to a non-rotatable part of the center shaft.
 12. Thestructure of claim 4, and electrical control circuitry for said drivemotor and coacting electrical means disposed inside of said centershaft.
 13. The structure of claim 3, and said center shaft comprisingfixed and rotatable sections, said rotatioNal speed changing driveincluding a gear element anchored to one of said sections of the centershaft, a coacting deflectable gear element attached to the other of saidsections and positioned to engage the first-named gear element, aneccentric operator for said deflectable gear element connected with anddriven by said motor and operable to create a circumferentiallytraveling deflection wave in the deflectable gear element to therebyinduce relative rotation between said deflectable and first-named gearelements, and a centrifugal force actuated brake means connected withand driven by said eccentric operator and adapted when activated toarrest relative rotation between said fixed and rotatable sections ofthe center shaft.
 14. The structure of claim 13, and said deflectablegear element comprising a thin-walled cup-like element arranged withinthe first-named gear element, the first-named gear element being a ringgear, a brake drum arranged inside of said cup-like element and securedto one of said sections of the center shaft, and said brake meanscomprising radially expansible brake shoes arranged inside of said drum.15. The structure of claim 13, wherein the first-named gear element isanchored to said fixed section of the center shaft and said deflectablegear element is attached to the rotatable section of the center shaft.16. The structure of claim 13, and said first-named gear element isanchored to the rotatable section of the center shaft, and saiddeflectable gear element is attached to the fixed section of the centershaft.
 17. The structure of claim 13, and a driving shaft for said brakemeans having a connection with said eccentric operator and coupled withand driven by said drive motor.
 18. The structure of claim 17, and aone-way active clutch coupling between said driving shaft and motor. 19.The structure of claim 18, and said eccentric operator comprising anelliptical bearing element coupled to said driving shaft and engaginginside of said deflectable gear element.